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I I w 2 1 Letters Patent 75,608, dated March 1'i, 1868; anteclatepl rfllarck 6, 1868. I

I PROVEMENT. IN EXTRAOTING TANNIN' Peon BARK.

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To ALL WHOM 1rM rconcE1in= v v Be it known that I, GARDNER-WARREN, of Roxbury, in the countyof -Norfolk, and State of Massachusetts,

have invented anew and useful Mode for the Treatment of Barlg in a Proeess for Obtaining Extracts of its then, that-' Tanning or 'otherlProp'crties; and I do hereby declare the'following to be a correct description of the same.

For the purpose of making myself more clearly understood, I shall divide the following description of my said invention into as many articles as there are different stages'in the progress of the process. I will say,

First."I steam the bark in a suitableapparatus provided forthat'purpose, the action-of the steam being to open the pores thereof, and tozexpel the air therefrom, so as .to admit-of its being rapidly saturated withwa-ter in a perfect manner. v I

Second. Having steamed the bark for a length of time suitable to the end of the purpose just set forth, I

' then immerse it in pater, which,by condensing the steam, speedily penetrates every pore of the bark, absorbing ;a portion of the soluble or tanning properties thereof.

.llhird. In the method which I'prefer, the bark, after having been sufiiciently saturated with the water for a'length of time sufiicient for it to have dissolved to the water that par-t .of the tanning property that is first and most speedily yielded to said solvent, is'taken and passed between pressing-rollers, of any suitable con struction, operated byproper machinery, heing thereby subjected to a pressure that will expel from its pores the liquor formed by the combination of the watenn'ith the soluble properties of said bark.

Fourth. The bark, as it is taken from the rollers, is again steamed-saturated with water, and passed between .the rollers, as just set forth, and this operati'on is repeated untilall of the tanning propertyis extracted, about three repetitions of the operation being found the most desirable.

Fifth. The liquors obtained hy the several operations. are kept separated, so that those obtained from the first, second, and third thereof are kept distinct, the one from the other. If the rollers or other. meansof pressure were not used, and a process of leaching weresubstitute'd therefor,.I would make the same subdivision thereof as 'I do when the pressure-rollers aroused, keeping the liquor produced by the first, second, and third lehchings separate from each other.

Sixth. The liquors thus obtained are now subjected to an evaporating-process, reducing the extract to any required consistency for marketing, the'divisions of the. liquor being preserved so as to form the'samc numbers and qualities of the extractso obtained. The greatadvantage results from the separationof the extract obtained intmtwo or more qualities, for, in extracting the tanning property of bark, it will be found that the part thereof which first yieldedrto the water is of superior quality for use in tanning calf-skins and other of the finer qualities of leather, as it renders it softer and more pliable than if the same were tanned in a liquor that had absorbed thewhole 01' thegreater part of the tanning property-of a given quantity of bark.

From this it is apparent that the division of the tanning-extracts into two or more grades orqualities is of" great value, as that 'part orquality which will produce leather of thesoftest and most pliable texture may be used in the manufacture of that which will have its market value the most enhanced by being possessed of those qualities, such as calf andkip-skins, and that grade which produces the harshest and least pliable leathermay be used with the best advantagein'producing such kind of leather as requires to be more rigid and firm. For'this reason, I deem 'itjb'est that the extract should be separated into three grades, the first of which could be used for tanning calf-skin and otherfine qualitie s of leather} the scc ond,-for producing cow-hides and other heavy grades; and the third, for manufacturing sole-leather: I

. :The value of my in ventio'n is found, in'part, in the saving of time wherein the tannin is extracted from the bark; and further, and to a much greaterdegree, its value is found in the grading of the extracts obtained, so that the finer qualities of leather may-beiproducod of asofter and more flexible-texture than any now known to cheered-e and for thepurpose of keeping these qualities-of the extracts as distinct as possible, I make the first pres'sure of the bark in the rollers much less than in the'subsequent operations, as the'propertiesthat go to mak'e -np the 'first extract are more soluble than the others. What I claim, and desireto secure by Letters Patent, is-- 1. The method of treating bark, for the purpose of obtaining its tanning or other qualities, by the three operations of steaming, soaking,.and squeezing the same, substantially as described.

2. The method of preparing several qualities of extracts from the same bark, by preserving the products of the several successive pressings separate from eah other, substantially asdl'scriberl.

Executed this 14th day of August, 1867.

GARDNER. WARREN Witnesses:

(hms. A. JORDAN, Wu. C. HIBBARD'. 

